Cartridge heater

Claim 1

AN ELECTRIC CARTRIDGE HEATER OF THE CHARACTER REFERRED TO INCLUDING, AN ELONGATE TUBULAR METAL SHEATH WITH A CLOSED INNER END AND AN OPEN OUTER END, A PLURALITY OF SUB-ASSEMBLIES EACH COMPRISING AN ELONGATE CYLINDRICAL CORE OF GRANULAR MAGNESIUM OXIDE AND A COIL OF RESISTANCE WIRE WOUND HELICALLY ABOUT THE CORE AND EXTENDING FROM ONE END THEREOF TO THE OTHER, SAID SUB-ASSEMBLIES BEING ARRANGED IN AXIAL ALIGNMENT AND CENTRALLY WITHIN THE SHEATH, AN ELONGATE PRIMARY CONTACT ROD WITH AN INNER PORTION WITHIN THE SHEATH, EXTENDING LONGITUDINALLY THROUGH THE SEVERAL CORES, A COUPLER UNIT SECURING THE INNER END OF THE COIL ON THE INNERMOST CORE TO THE INNER END OF THE PRIMARY ROD, A PLURALITY OF ELONGATE CONNECTOR PINS EXTENDING LONGITUDINALLY BETWEEN AND INTO THE OPPOSING END PORTIONS OF ADJACENT CORES, IN LATERAL SPACED PARALLEL RELATIONSHIP WITH THE PRIMARY CONTACT ROD AND RADIALLY INWARDLY OF THE COILS, COUPLING UNITS CONNECTING THE ENDS OF THE COILS AT THE SAID OPPOSING ENDS OF THE CORES TO THE PINS, A SECONDARY CONTACT ROD WITH AN INNER PORTION ENGAGED IN THE OUTER END OF THE OUTERMOST CORE IN AXIAL ALIGNMENT WITH THE PINS, A COUPLER UNIT CONNECTING THE OUTER END OF THE COIL ON THE OUTERMOST CORE TO THE SECONDARY CONTACT ROD, A PLUG DIELECTRIC MATERIAL ENGAGED IN THE OUTER END OF THE SHEATH AND THROUGH WHICH THE OUTER PORTIONS OF THE RODS EXTEND AND A FILLER OF GRANULAR MAGNESIUM OXIDE IN THE SHEATH AND ABOUT THE PARTS ARRANGED THEREIN.